The discovery of mirror neurons (MNs) in the monkey has been one of the most important advances of our knowledge about the role of the motor system in action perception. More impor-tantly, this discovery has attracted the attention of scientists from many disciplines because of its possible implications in explaining important aspects of primate social cognition such as the under-standing of others'goals and acfions (Jeannerod 1994;Rizzolatti et al. 2001). More recent neurophysiological and neuroimaging studies are giving significant impulse to our understanding of the mirror neuron system (MNS) and are raising questions concerning their specific functions. Some researchers have argued that this system is precociously funcfioning since infancy in both humans and monkeys (Lepage &Theoret 2006;Ferrari et al. 2006) and prob-ably serving very basic functions in early social interactions. These functions might constitute im-portant precursors of higher order socio-cognitive skills fully expressed in adulthood. Among them, particularly relevant is the capacity to understand others'intentions since it can impact individual's decisions in determining the course of social interactions. A lack of such social comprehension might compromise basic social faculties necessary for everyday life. The primary objective of the project is to understand the developmental trajectory characte-rizing the early functioning of the MNs in monkeys with respect to later development of high order socio-cognitive skills and, secondly, to elucidate the involvement of MNs in such skills. The project consists of two interrelated parts. The specific aim of the first part is to track longitudinally the relation between early behavioral markers of MN and the development of sociocognitive skills. The specific aim of the second part is to investigate how MN integrate information about the social con-text with that of the observed agent's action. This neural mechanism enables the monkey to under-stand the intention of the observed agent which is crucial to make appropriate decisions and to determine future social interactions.